GATE ECE 1992 | Question 1.29

Question

Which of the following signals is/are periodic?

• A. $\mathrm{S}(t)=\cos 2 t+\cos 3 t+\cos 5 t$
• B. $\mathrm{S}(t)=\exp (j 8 \pi t)$
• C. $S(t)=\exp (-7 t) \sin 10 \pi t$
• D. $S(t)=\cos 2 t \cos 4 t$

Answer 1